[ 148 ] 



XXVII. On the apparent Elevation of OhjeSls ahove the Hor'i- 

 'zon. Bj ProfeJor'DE hvc*. 



I 



T is well known, that on the borders of lakes, the banks 

 ot broad rivers, and the lliore of bays, a certain optical illn- 

 fion often takes place when the fpeciator is ftationed in a high 

 point ot view. The oppofite bank, under certain circum- 

 liances, isfeenas it were floating in the air ; and this phaeno- 

 ricnon is aicribed to refraction : but in my opinion it proceeds 

 from a different caufe. 



About two years ago lobferved the phsenomcnon in quef- 

 tion in on*.- of thofe cxtcnfive turf moors that occur fo often 

 among the heights in Eremcrlande, through which I was 

 then travelling. The trees which bordered this moor, to- 

 wards the lionzon, appeared to me to be floating in the air. 

 I at firft conjeclured, according to analogy, that there muft 

 be a lake or river at the end of the turf moor ; but the poftil- 

 lion who drove the carriage affured ine that this was not the 

 cafe. 



In the month of July this year, being in the fame diftriiSl, 

 I faw afimilar phaenomenon, and under circumftances which 

 induced me to examine it with more attention. I was on 

 the road between Bremcrvorde and Brcderkefa, proceeding 

 in a north-eaft direction. It was about nine in the morning ; 

 the heavens were covered with light clouds, yet the fun ap- 

 peared through them a little behind me on the right, and 

 over a turf moor which extended to the horizon, and was bor- 

 dered with a row of trees. When the pha:nomcnon firll ap- 

 peared, I was travelling down an eminence on a road adjacent 

 to the edge of the moor^ which entered it a little wav, and 

 then proceeded up an oppofite hill. The variations which I 

 obferved in the phcenomenon as I advanced (lowly down the 

 hill, induced me to difmount, that I might be able every now 

 and then to turii back. \V hat I obferved on this occafion was 

 as follows : 



At the moment when I was about to defcend, I could fee 

 and obfervc ♦rom the higheli; point of the hill a very large 

 furface of the turf moor, which extended itfelf with increafing- 

 breadth towards the horizon ; the diliance of which I e(ti- 

 mated at a German mile. From this pretty high point of 

 fight, I could perceive that the trees at the extremity of the 

 moor did not itand exactly in a line, but that they forn»ed a 

 fort of wood, which extended backwards on the other lidc, 



* From Drr GcJctljibaftNat:trfjrfLh>icJu FietouL zu Balin Nt ue Hcbrifioif 

 vol. lii. iboi. 

 ;"^ ' ' and, 



